<template>
  <div class="s-canvas" ref="wrapper">
    <canvas
      id="s-canvas"
      :width="contentWidth"
      :height="contentHeight"
    ></canvas>
  </div>
</template>
<script>
export default {
  name: "SIdentify",
  props: {
    identifyCode: {
      //默认注册码
      type: String,
      default: "123"
    },
    fontSizeMin: {
      // 字体最小值
      type: Number,
      default: 25
    },
    fontSizeMax: {
      // 字体最大值
      type: Number,
      default: 35
    },
    backgroundColorMin: {
      // 验证码图片背景色最小值
      type: Number,
      default: 200
    },
    backgroundColorMax: {
      // 验证码图片背景色最大值
      type: Number,
      default: 220
    },
    dotColorMin: {
      // 背景干扰点最小值
      type: Number,
      default: 0
    },
    dotColorMax: {
      // 背景干扰点最大值
      type: Number,
      default: 0
    },
    contentHeight: {
      //容器高度
      type: Number,
      default: 38
    }
  },
  data() {
    return {
      contentWidth: 120,
      readyPromise: null,
      readyPromiseRS: null,
      readyPromiseRJ: null
    };
  },
  methods: {
    // 生成一个随机数
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min);
    },
    // 生成一个随机的颜色
    randomColor(min, max) {
      let r = this.randomNum(min, max);
      let g = this.randomNum(min, max);
      let b = this.randomNum(min, max);
      return "rgb(" + r + "," + g + "," + b + ")";
    },
    drawPic() {
      this.readyPromise.then(() => {
        let canvas = document.getElementById("s-canvas");
        let ctx = canvas.getContext("2d");
        ctx.textBaseline = "bottom";
        // 绘制背景
        ctx.fillStyle = this.randomColor(
          this.backgroundColorMin,
          this.backgroundColorMax
        );
        ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
        // 绘制文字
        for (let i = 0; i < this.identifyCode.length; i++) {
          this.drawText(ctx, this.identifyCode[i], i);
        }
        this.drawLine(ctx);
        this.drawDot(ctx);
      });
    },
    drawText(ctx, txt, i) {
      ctx.fillStyle = this.randomColor(50, 160); //随机生成字体颜色
      ctx.font =
        this.randomNum(this.fontSizeMin, this.fontSizeMax) +
        "px MicrosoftYaHei"; //随机生成字体大小
      let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
      let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
      var deg = this.randomNum(-30, 30);
      // 修改坐标原点和旋转角度
      ctx.translate(x, y);
      ctx.rotate((deg * Math.PI) / 180);
      ctx.fillText(txt, 0, 0);
      // 恢复坐标原点和旋转角度
      ctx.rotate((-deg * Math.PI) / 180);
      ctx.translate(-x, -y);
    },
    drawLine(ctx) {
      // 绘制干扰线
      for (let i = 0; i < 1; i++) {
        ctx.strokeStyle = this.randomColor(100, 200);
        ctx.beginPath();
        ctx.moveTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        );
        ctx.lineTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        );
        ctx.stroke();
      }
    },
    drawDot(ctx) {
      // 绘制干扰点
      for (let i = 0; i < 3; i++) {
        ctx.fillStyle = this.randomColor(0, 255);
        ctx.beginPath();
        ctx.arc(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight),
          1,
          0,
          2 * Math.PI
        );
        ctx.fill();
      }
    }
  },
  watch: {
    identifyCode: {
      handler(val) {
        if (val) {
          this.drawPic();
        }
      },
      deep: true,
      immediate: true
    }
  },
  created() {
    this.$nextTick(() => {
      this.contentWidth = this.$refs.wrapper.clientWidth;
    });
    this.readyPromise = new Promise((resolve, reject) => {
      this.readyPromiseRS = resolve;
      this.readyPromiseRJ = reject;
    });
  },
  mounted() {
    this.readyPromiseRS();
  }
};
</script>
<style scoped lang="less">
#s-canvas {
  border: 1px solid @oranges;
  border-radius: 1rem;
}
</style>
